In order to test our Williams CPU, ROM, I/O and Sound boards I’ve decided it’s time to invest some time and effort and build a complete Williams Test Rig.

The goals of the rig are:

– Allow testing of all Williams boards (CPU, ROM, I/O, Sound)
– Allow testing of all Williams games (Defender, Stargate, Joust, Robotron, etc.)
– Be easily store-able
– Not need an arcade monitor to test



1 x plank of wood to host the boards
1 x pack of RS Electronics PCB mounts and screws


1 x Linear power supply for desk testing
1 x ATX Power Supply Male and Female connector (for easily switching between the linear power supply and the original power connector)


1 x CGA to VGA connector to SVGA connector from eBay ($6.95)
1 x SVGA to SVGA lead
1 x RGB to SVGA upscaler from eBay ($22.49)
1 x SVGA to SVGA lead (to monitor)
1 x SVGA monitor


1 x Williams Defender wiring harness (from sadly deceased machine someone else broke via eBay US)
1 x extra combined Sync wiring to pin 7 of the Williams video connector
1 x Sound -> Rom connector
1 x Volume POT
1 x Speaker
1 x Williams Defender control panel wiring (from same sadly deceased machine above)


1 x Williams Defender ROM, CPU, Sound and I/O Board

Step 1: Mark the board positions and drill holes for mounting screws.

Wooden shelf with drill points

Step 2: Screw in the PCB mounting screws

Can you tell what it is yet?

and from the side...

Step 3: Add the Williams Defender boards and start connecting up the wiring harness

Looking more like a Defender now :-)

Continued in Part 2 ->